This invention relates to the distribution of video signals and, more particularly, to controlling the distribution of the video signals.
Distribution of video signals to one or more outlets at a location is now typically realized by the use of coaxial cable (COAX). In addition, video terminals connected to the one or more outlets are for the most part analog television sets (TVs). Recently, digital broadband access systems have been proposed, e.g., cable modem, fiber-to-the-home, or the like, which would deliver MPEG2 (Motion Picture Experts Group 2) standard digital video signals. These digital signals must be converted to analog video signals consistent with available TVs, and with COAX signals expected by cable ready TVs. A known approach is the use of an individual set-top-box for each TV, which includes a MPEG2 decoder, a digital-to-analog (D/A) converter, a NTSC (National Television Systems Committee) encoder and a frequency up-converter to deliver the video at the frequency of a selected channel. Typically, the use of an individual set-top-box per TV assumes the availability of all desired video channels at an input of each of the set-top-boxes. The need to deliver all channels to each set-top-box is an inefficient use of the broadband access system. Furthermore, the use of such individual set-top-boxes is inefficient, cumbersome and costly. The inefficiency results because typically only a few of the TVs and associated set-top-boxes are active at any given time.
Limitations and problems of prior known video signal distribution systems are overcome by employing a single centralized video controller to convert and distribute video channels to one or more analog TVs, i.e., viewing devices or the like. This is realized without the need for changes to either the TVs or the interconnecting COAX, and without the use of a set top box per TV. Indeed, only a remote control unit is needed for each TV. Specifically, the centralized controller includes one or more MPEG2 decoders, the number of which depends on a desired number of active TVs to be used in viewing different video programs on different channels, and one or more wireless, e.g., radio frequency (RF) or infra red, communications links to television controllers, i.e., remote control units, associated on a one-to-one basis with the desired number of TVs.
In operation, channel selection for each of the one or more TVs is typically communicated up-stream from the centralized controller to a video server and a video services controller, therein. The video server only transmits the selected channels to the local centralized video controller. However, when the video channel is already being supplied from the video server to an optical line terminal and, specifically, to an optical line card to which the requesting centralized controller is connected to, there is no need to communicate the channel request to the video server. The optical line terminal simply supplies the requested channel via an optical line card to the additional requesting centralized controller and, in turn, to the requesting TV.
In one embodiment of the invention, each of the one or more active TVs, is assigned one of a plurality of program units included in the centralized controller, and is switched to a video channel that is supplied an analog video signal by the program unit. In this embodiment, each program unit includes a broadband asynchronous transfer mode (ATM) virtual channel (VC) filter, a MPEG2 decoder, a NTSC encoder and a frequency up-converter. The MPEG2 decoder decodes a video signal supplied via the VC and supplies the analog version of the decoded video signal as its output. The analog video signal is NTSC encoded and up-converted to a fixed video channel. The video channel designation corresponds to the assigned MPEG2 decoder and is specified by the centralized video controller. The video channel number is transmitted to the TV remote control unit via a first wireless link and, then, supplied to the TV tuner via an infra red (IR) wireless link. Additionally, the remote control unit communicates channel selections via the first wireless link to the centralized video controller that, in this example, passes the channel selections to a video services controller in a video server using an up-stream communications link. In this example, the up-stream communications link is a broadband ATM VC. In response to the communicated channel selections, the video server transmits the selected channel to the centralized video controller using a down-stream communications link. In this example, the down-stream link is a constant bit rate (CBR) ATM VC. Consequently, the digital video signal is supplied to the centralized video controller as a continuous stream of ATM cells, while the up-stream communications is transmitted as bursts. In this example, a specific VC is statically assigned to each conventional broadcast video channel and other VCs are dynamically assigned for other video services, for example, video-on-demand, or the like. If the program units are all in use supplying video channels to active TVs, additional TVs can tune to any of the supplied video channels but they do not have any xe2x80x9cprogramxe2x80x9d selection capability.
In another embodiment of the invention, the up-converter included in each program unit is frequency agile. A video channel selected via the remote control unit is communicated to the centralized video control unit via the first wireless link and is transmitted up-stream to the video server and the video services controller, therein. The selected video program channel is also supplied to the TV tuner via the IR wireless link. Additionally, the MPEG2 decoded video signal is transmitted on the selected program channel. This is realized by dynamically controlling the channel that the video signal is up-converted to by the agile up-converter. Indeed, as the channel selections are made, the associated remote control unit transmits the channel designation to both the TV tuner and the centralized video controller using the IR wireless link and the first wireless link, respectively.
In still another embodiment of the invention, the up-converter has a fixed frequency, i.e., video channel, which is assigned to an associated MPEG2 decoder.